Ultraselective Extraction Reprocessing of 99TcO4-/ReO4- with a Promising Carbamic Acid Extractant System.

Abstract

With the development of nuclear energy, the reprocessing of 99TcO4-/ReO4- has become a very difficult problem due to environmental issues such as high output, long life, and easy leakage. In this study, three extraction systems containing carbamic acid were introduced into the reprocessing of 99TcO4-/ReO4- for the first time. The results involving one of the three results show that N-[N,N-di(2-ethylhexyl) aminocarbonylmethyl] glycine (D2EHAG) has ultrahigh selectivity for removal to 99TcO4-/ReO4-. When the extreme concentration ratio of SO42- and Cl- to ReO4- of D2EHAG is 10,000:1, the distribution coefficient of ReO4- still reaches 12.73 and 2.67, respectively. Additionally, the most hydrophilic NO3-, when the extreme concentration ratio of NO3- and ReO4- is 1000:1, still has a distribution coefficient close to 2.33, which is more than the most reported MOF adsorption materials. Moreover, the reaction kinetics, stripping rate, and reuse rate were studied. After five cycles, the removal rate is still 98.12%, with a decrease of less than 0.7%. The system containing carbamic acid is a potential extraction removal system to remove 99TcO4-/ReO4- from nuclear radioactive wastewater.